1. Field of the Invention
The present invention relates to high energy loss fluid flow control devices and more particularly relates to devices sometimes known as let down valves and the like used for reducing the pressure of fluids received from high pressure systems to lower levels for exhausting to the atmosphere or for use in systems operating at lower pressures. Devices in accordance with the present invention are useful in the controlled reduction of fluid pressures from very high process pressures down to atmospheric pressure or less as may be used in low pressure systems. In the petroleum industry, devices of this general category are often called chokes or throttling valves and similar devices are used in submarines for discharging air from ballast tanks into the water in a controlled manner with low noise level being a requisite. Devices in accordance with the invention are also useful for flashing of high pressure liquids into gases or for rapid expansion of gases to much lower pressures for cooling application. High pressure loss fluid flow control devices are also useful in coal gasification systems and in liquification systems wherein the working fluid medium is at high pressure and high temperature and also contains abrasive solid particles such as char.
2. Description of the Prior Art
Several high pressure fluid energy loss control devices are shown in U.S. Pat. Nos. 3,451,404; 3,513,864; 3,207,181; 3,331,396; 3,426,797 and 3,514,074. The devices shown in these prior art patents utilize a plurality of parallel flow passages and in some of the devices the passages are formed by a plurality of disks having slots or grooved passageways formed therein. In the disk devices the fluid pressure is reduced in discrete steps or increments and is not a continuous and smooth pressure reduction and in some devices the flow area is changed by adding or subtracting parallel flow paths.
It is an object of the present invention to provide a new and improved high energy loss fluid flow control device.
More particularly, it is an object of the invention to provide a device of the character described suitable for use in coal gasification systems wherein the fluid medium is solid particles such as char particles. a high pressure, high temperature, and contains highly abrasive solid particles such as char particles.
Another object of the invention is to provide a new and improved high energy loss fluid flow control device of the character described wherein a maximum pressure drop is obtained with a minimum of noise being generated.
Another object of the invention is to provide a new and improved high energy loss fluid flow control device of the character described wherein a maximum pressure drop is obtained with a minimum of noise being generated.
Another object of the present invention is to provide a new and improved fluid flow control device of the character described which provides a continuous pressure reduction from high pressure to low pressure without discrete steps or increments.
Another object of the present invention is to provide a new and improved high pressure fluid flow control device wherein the cross-sectional area of the flow passage is continuously and gradually increased and wherein the length of the continuous passage is adjustable.
Another object of the present invention is to provide a device of the character described wherein both length and the cross-sectional area of the continuous flow passage is adjustable to provide the desired expansion ratio.
Another object of the present invention is to provide a new and improved device of the character described wherein a flow restriction is provided upstream of a valve seating surface to prevent high velocity flow during the initial opening of the valve.
Another object of the present invention is to provide a new and improved flow control device of the character described wherein surfaces defining the continuous flow passage on the valve member and housing do not come into direct contact with one another.
Another object of the present invention is to provide a new and improved fluid flow control device suitable for use in flashing liquids to gas.
Another object is to provide a device suitable for use with fluid slurries containing solid particles and the like.
Another object of the present invention is to provide a new and improved high energy loss fluid flow control device wherein the length and/or flow area of a continuous flow passage is infinitely variable to provide a continuously variable throttling action of the fluid medium.
Another object is to provide a new and improved high energy loss fluid flow control device wherein relative rotation or grinding action between the valve and a seating surface is provided so that contamination solids or particles that may have collected on the seating surfaces during operation are readily removable.
Another object of the present invention is to provide a new and improved high energy loss fluid flow control device having the capability of handling high temperature fluid medium up to the range of 2100.degree. F. through utilization of simplified ceramic construction.
Still another object of the present invention is to provide a new and improved device of the character described wherein the member is movable relative to a seat with both rotary and linear action and wherein both axial and circumferential helical flow through the device is controllable to control both the amount of fluid turbulance and the pressure loss for a particular flow area.
Another object of the present invention is to provide a high energy loss fluid flow control device having a throttle passage of helical configuration having a length which is variable to provide the desired expansion ratio.
Still another object of the present invention is to provide a high energy loss fluid flow control device having a continuously increasing flow area from the high pressure inlet to the low pressure outlet.
Another object is to provide a new and improved flow control device of the character described which has no sharp notches, corners or edges that might act as points of stress concentration.
Another object of the invention is to provide a new and improved flow control device of the character described having a flow passage defined by elements and surfaces entirely formed in part of ceramic material.